The urban heat island (UHI) effect is the warming of urbanized areas relative to their surrounding, vegetated, rural regions. Traditional building and infrastructure materials — like concrete and asphalt pavements — retain more heat during the day and release it back into the environment, increasing surrounding temperatures. Coupled with summer heat, urban heat has implications for all of us, because excessive heat:
- Negatively impacts health and well-being by exacerbating chronic and acute conditions (which increase emergency room visits and death rates, particularly for the most vulnerable populations);
- Increases electricity use — which can increase the costs for cooling, stress power generation and transmission systems, and increase greenhouse gas emissions;
- Negatively impacts our economy by reducing agricultural and labor productivity, among other factors;
- Impairs water quality and increases the volume of water required to keep trees and landscape alive and healthy.